In recent years, owning to excellent display effect of an organic light emitting diode (OLED) display, development of OLED-related industry at home and abroad is booming, and various pixel circuits have been developed one after another.
In the process of practical production and fabrication for thin film transistors (TFTs), excimer laser annealing (ELA) and doping processes cannot guarantee that the TFTs have good a uniformity, which results in the occurrence of threshold voltage deviation and mobility deviation, wherein the mobility is related to μ in a current formula. For a most basic 2T1C (two TFTs having a function of switching, and one capacitor having a function of storing charges) circuit, when a same data signal (Data) is written, brightness of respective pixels would be non-uniform due to different Vth and μ existing in the current formula, thereby causing problems of bad display, and influencing the display effect of the OLED display.